Propionic acidemia is an inherited disorder of protein metabolism which is associated with recurrent bouts of vomiting and lethargy, metabolic keto-acidosis and hyperammonemia, usually requiring admission to the hospital. Intestinal transit in children with propionic acidemia will be studied to systematically correlate a relationship between intestinal transit and metabolic stability. If found, there may be an indication for regular treatment with gut motility agents in this population.